The overall objective of this contract is to facilitate discovery and development of therapies with potential for treatment and prophylaxis of Pneumocystis carinii pneumonia in people with AIDS. The expected performance of this contract is to quantitatively evaluate therapeutic agents for efficacy against Pneumocystis carinii pneumonia in a standardized, validated mouse model test system, to include evaluation of therapies in combination in the primary mouse model, drug evaluations in prophylaxis protocols in the primary mouse model, and evaluation of treatment therapies in a rat model. Therapeutic agents will be evaluated for activity in a standardized, reproducible and validated in vitro (culture) test system which employs intact organisms.